Cassini: Saturn probe’s death plunge

The international Cassini spacecraft at Saturn has executed the course correction which will inevitably send it to destruction at the end of the week.

The probe flew within 120,000km of Titan on Monday – an encounter which bent its trajectory enough to place it on a collision path with Saturn.

Now, it is inevitable that Cassini will plunge into Saturn’s atmosphere on Friday. The spacecraft will dismantle as it heads towards the clouds.

Since it arrived at Saturn 13 years ago, the probe has harnessed the gravity of Titan – the second largest moon in the Solar System – to slingshot itself into differing positions from which to study the planet and its surrounding rings.

The strategy has meant that Cassini has not had to fire up its propulsion system, which would consequently drain its fuel reserves when making large changes in direction.

Earl Maize, Cassini project manager at NASA’s Jet Propulsion Laboratory, Pasadena, California, said: “Cassini has been in a long-term relationship with Titan, with a new rendezvous nearly every month for more than a decade.

“This final encounter is something of a bittersweet goodbye, but as it has done throughout the mission, Titan’s gravity is once again sending Cassini where we need it to go.”

In 2005, the spacecraft put a small robot called Huygens on its surface. From this it returned an image of rounded pebbles that had been smoothed by the action of flowing liquid methane. The hydrocarbon rains from Titan’s orange sky, running into huge seas at northern latitudes.

Cassini also observed what are assumed to be volcanoes, which expel an icy slush, and vast dunes made from a plastic-like sand.

The investigation of Titan – a 5,150km-wide moon – has been one of the outstanding successes of the Cassini mission. The probe recently passed Titan, gathering images and scientific data, which will be streamed back to Earth on Tuesday.

The Cassini-Huygens mission is a joint endeavour between NASA, and European and Italian space agencies.